Two related superfamilies of putative helicases involved in replication, recombination, repair and expression of DNA and RNA genomes

Nucleic Acids Res. 1989 Jun 26;17(12):4713-30. doi: 10.1093/nar/17.12.4713.


In the course of systematic analysis of protein sequences containing the purine NTP-binding motif, a new superfamily was delineated which included 25 established or putative helicases of Escherichia coli, yeast, insects, mammals, pox- and herpesviruses, a yeast mitochondrial plasmid and three groups of positive strand RNA viruses. These proteins contained 7 distinct highly conserved segments two of which corresponded to the "A" and "B" sites of the NTP-binding motif. Typical of the new superfamily was an abridged consensus for the "A" site, GxGKS/T, instead of the classical G/AxxxxGKS/T. Secondary structure predictions indicated that each of the conserved segments might constitute a separate structural unit centering at a beta-turn. All previously characterized mutations impairing the function of the yeast helicase RAD3 in DNA repair mapped to one of the conserved segments. A degree of similarity was revealed between the consensus pattern of conserved amino acid residues derived for the new superfamily and that of another recently described protein superfamily including a different set of prokaryotic, eukaryotic and viral (putative) helicases.

Publication types

  • Comparative Study

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Bacterial Proteins / genetics
  • DNA Helicases / genetics*
  • DNA Helicases / physiology
  • DNA Repair*
  • DNA Replication*
  • DNA, Viral / genetics*
  • Fungal Proteins / genetics
  • Humans
  • Molecular Sequence Data
  • Multigene Family*
  • Nucleoside-Triphosphatase
  • Phosphoric Monoester Hydrolases / metabolism
  • RNA, Viral / genetics*
  • Recombination, Genetic*
  • Viral Proteins / genetics


  • Bacterial Proteins
  • DNA, Viral
  • Fungal Proteins
  • RNA, Viral
  • Viral Proteins
  • Phosphoric Monoester Hydrolases
  • Nucleoside-Triphosphatase
  • DNA Helicases